#include<bits/stdc++.h>
using namespace std;
namespace fastio
{
    const int bufl=1<<20;
    const double base1[16]={1,1e-1,1e-2,1e-3,1e-4,1e-5,1e-6,1e-7,1e-8,1e-9,1e-10,1e-11,1e-12,1e-13,1e-14,1e-15};
    const double base2[16]={1,1e1,1e2,1e3,1e4,1e5,1e6,1e7,1e8,1e9,1e10,1e11,1e12,1e13,1e14,1e15};
    struct IN{
        FILE *IT;char ibuf[bufl],*is=ibuf,*it=ibuf;
        IN(){IT=stdin;}IN(char *a){IT=fopen(a,"r");}
        inline char getChar(){if(is==it){it=(is=ibuf)+fread(ibuf,1,bufl,IT);if(is==it)return EOF;}return *is++;}
        template<typename Temp>inline void getInt(Temp &a){a=0;int b=0,c=getChar();while(c<48||c>57)b^=(c==45),c=getChar();while(c>=48&&c<=57)a=(a<<1)+(a<<3)+c-48,c=getChar();if(b)a=-a;}
        template<typename Temp>inline void getDouble(Temp &a){a=0;int b=0,c=getChar(),d=0;__int128 e=0,f=0;while(c<48||c>57)b^=(c==45),c=getChar();while(c>=48&&c<=57)e=(e<<1)+(e<<3)+c-48,c=getChar();if(c==46){c=getChar();while(c>=48&&c<=57)d++,f=(f<<1)+(f<<3)+c-48,c=getChar();}a=e+base1[d]*f;if(b)a=-a;}
        IN& operator>>(char &a){a=getChar();return *this;}
        IN& operator>>(char *a){do{*a=getChar();}while(*a<=32);while(*a>32)*++a=getChar();*a=0;return *this;}
        IN& operator>>(string &a){char b=getChar();while(b<=32)b=getChar();while(b>32)a+=b,b=getChar();return *this;}
        IN& operator>>(int &a){getInt(a);return *this;}
        IN& operator>>(long long &a){getInt(a);return *this;}
        IN& operator>>(__int128 &a){getInt(a);return *this;}
        IN& operator>>(float &a){getDouble(a);return *this;}
        IN& operator>>(double &a){getDouble(a);return *this;}
        IN& operator>>(long double &a){getDouble(a);return *this;}
    };
    struct OUT{
        FILE *IT;char obuf[bufl],*os=obuf,*ot=obuf+bufl;int Eps;long double Acc;
        OUT(){IT=stdout,Eps=6,Acc=1e-6;}OUT(char *a){IT=fopen(a,"w"),Eps=6,Acc=1e-6;}
        inline void ChangEps(int x=6){Eps=x;}
        inline void flush(){fwrite(obuf,1,os-obuf,IT);os=obuf;}
        inline void putChar(int a){*os++=a;if(os==ot)flush();}
        template<typename Temp>inline void putInt(Temp a){if(a<0){putChar(45);a=-a;}if(a<10){putChar(a+48);return;}putInt(a/10);putChar(a%10+48);}
        template<typename Temp>inline void putLeading(Temp a,int b){if(!b)return;putLeading(a/10,b-1);putChar(a%10+48);}
        template<typename Temp>inline void putDouble(Temp a){if(a<0){putChar(45);a=-a;}__int128 b=a;putInt(b);a-=b;a*=base2[Eps];b=a+Acc;putChar(46);putLeading(b,Eps);}
        OUT& operator<<(char a){putChar(a);return *this;}
        OUT& operator<<(char *a){while(*a>32)putChar(*a++);return *this;}
        OUT& operator<<(string a){for(auto c:a)putChar(c);return *this;}
        OUT& operator<<(int a){putInt(a);return *this;}
        OUT& operator<<(long long a){putInt(a);return *this;}
        OUT& operator<<(__int128 a){putInt(a);return *this;}
        OUT& operator<<(float a){putDouble(a);return *this;}
        OUT& operator<<(double a){putDouble(a);return *this;}
        OUT& operator<<(long double a){putDouble(a);return *this;}
        ~OUT(){flush();}
    };
}
using fastio::IN;
using fastio::OUT;
IN fin;
OUT fout;
const int NN=6e6+4,dx[8]={0,0,1,-1,1,1,-1,-1},dy[8]={1,-1,0,0,1,-1,1,-1};
pair<int,int>d[NN];
bool vis[NN];
string s[3004];
int n,m,k;
int get(int x,int y)
{
	return (x-1)*m+y;
}
pair<int,int>split(int x)
{
	return {(x-1)/m+1,(x-1)%m+1};
}
int main()
{
	freopen("stamp.in","r",stdin);
	freopen("stamp.out","w",stdout);
	int x1,y1,x2,y2;
	fin>>n>>m>>k>>x1>>y1>>x2>>y2;
	for(int i=1;i<=n;i++)
	{
		fin>>s[i];
		s[i]=" "+s[i];
	}
	for(int i=1;i<=n*m;i++)
		d[i]={1e9,1e9}; 
	deque<int>q;
	q.push_back(get(x1,y1));
	if(s[x1][y1]=='.')
		d[get(x1,y1)]={0,0};
	else
		d[get(x1,y1)]={1,k-1};
	while(q.size())
	{
		int u=q.front();
		pair<int,int>t=split(u);
		q.pop_front();
		if(vis[u])
			continue;
		vis[u]=true;
		for(int i=0;i<(d[u].second?8:4);i++)
		{
			int nx=t.first+dx[i],ny=t.second+dy[i],v=get(nx,ny);
			if(nx>n||!nx||ny>m||!ny)
				continue;
			pair<int,int>w=d[u];
			if(w.second)
				w.second--;
			else
			{
				if(s[nx][ny]=='.')
				{
					if(d[v]>w)
					{
						d[v]=w;
						q.push_front(v);
					}
					continue;
				}
				w.first++,w.second=k-1;
			}
			if(d[v]>w)
			{
				d[v]=w;
				q.push_back(v);
			}
		}
	}
	fout<<d[get(x2,y2)].first;
	return 0;
}
